Gilbeit aebsi shaiespbak



G. A. SHAKESPEAR.

APPARATUS FOR THE DETECTION AND MEASUREMENT 0F GASES.

APPLICATION min bcT. is. ma.

Patented May 20, 1919.

UNITED STATES PATENT oFFrcE."

GILBERT man orrmumem, ENGLAND. I arrnmrus FoRATHn-nnrncrron on ceses.

To aillwlzom it may concern:

the employment of a Wheatstone bridge Asys-V versity, Birmingham, England, a subject of the King of Great Br'tain `and Ireland, have mvented certain new and useful Improve- -mentsRelating to Apparatus for the Detection and Measurement of Gases, of which the following is a Specification.

This invention has for its object to provide improvedv apparatus for the detection and measurement of a known constituent in a given gaseousmixture, the apparatusbeing'o the type in which the rate 'oflossof heat of a body exposed to the gaseous mixture is employed as the detecting and measuring agency. This invention consists in tem comprising a pair of electricallyheated wires, one of' which is surrounded by the gas to be' tested while the other is surrounded either by air orfby. any other gas which can serve as a standard for comparison, the deiiection of agalvanometer or the adjustment necessary to produce a state of balance in the system being employed to give the requiredmeasurement.` l In the accompanyingdiagrams, AFigure l illustrates the arrangement of a gas detecting or'measuring instrument constructed in accordance with this invention.

Fig. 2 shows an-application ofthe invention to detecting leakage of gases through fabrics.

Fig. 3 shows a modified form ofblock containing thedetecting wires.

Ordinarily I 'form a pair. of similar cavities a a a metal block b (Fig. 1') and in each arrangeone of a pair of'similar detectmg wires c. trically connected to the block and at the other end is insulated. Onev of the cavities (a) is hermetically sealed, 'but the other (a) by means of small perforations d in the ook is open to the external atmosphere. Each wire is arranged in series with another resistance e e andthe whole of the elements are connected as shown in the ,manner of the well known Wheatstone bridge system, a galvanometer f being provided across one pair 0f junctions and a battery' g' across another pair. The metal block b is adapted in any convenient manner to be inserted in a position where it` is freely v accessible to the' gas to be tested. Onclosing the circuit both wires in the block are. h eated. The amount A t one end each wire `is elec- Specification of Letters Patent; Patented 'May 2(1), 1919, application med october 15, 191s. serial No. amigas.4

1 ofheating permitted may varied, but ordi- Be it known that If, GILBERT Annnrr SHAKEsrnAm-D. Se., residing at The Uninarily a few degrees in excess of-the'normal temperature of the gas is suiicient. If 'the two gases surrounding the wires'iare'similar no deflection -will occur on the ga1va`nometer,`

but if one of them differs from the otherdue to thepresence of another gaseous constituent the balance'is disturbed. In all cases the average temperature ofthe two gases surrounding the wires is substantially the same;

T he instrument is calibrated so that either the galvanometer deflection, or the variation of resistance external to the wiresrequired to restore the balance gives the measure of mixture.

The invention may be appliedfor a variety of like purposes. Thus, it maybe utilized for the detection of leakage in the neighborhOOd of industrial gas holders, or for labora- 'tory analysesof gases of which the constitu- -ents are known, or for checking. the uniformity of gaseous mixtures used as anesthetics. Also, the-'invention isnotlunited to the cons tructional details herein descrlbed ample, a pairc'f pipes L v(I1`ig;.3) may provide communication through l'perforations d with each cavity .a a and a slow stream of a standard composition and the other-containing the gas to be detected. For testing the porosity or permeabllity of balloon or other fabrics vthe deviceshownv 'fitted with' detect- -asgthese may be varied in a number of ways to .meet diii'erent requirements.

Y gas may be passed through both, one having in Fig. 'v open by' way of lateral perorations to the chamberv j and any leakageof-gas through the fabric Y into the chamber is detected by the instrument, the deflection ofthe alvanometer in'- dicating the amount of lea age.

. Having thus described my invention 'what' I claim as new. land desire lto secure by Let- A Vters Patent is -1. In apparatus for the detection and measurement of'gase's, the combination oomprising a pair of detecting wires, a pair of reslstances and a galvanometerformmg av 11o4 Wheatstone bridge system, and ametal block having a pair of cavities each containing a 70 i the proportion of the said constituent 1n the detecting Wire, said block being povded with perforations between one of the Cavities and the exte'or of the block, substantaily as descrbe.

2. In apparatus fof the detection and measurement' of gases, the combination comprisilig a pair of resistances and a gaivanemeter fommg a,-

deteeting Wires, a pe-ir ef W/Vheatstoiie bridge system, mete beek having a pai' of cavities, and pipes whereby 10 dierent gases can be admitted te the Cavities, substantially as described.

in testiinony whereof have signed my name to this speeieation.

GLBEET RDEN SEMESPEAR. 

